Contact separation detector and methods therefor

ABSTRACT

A device, circuit, system, and method for contact separation detection is described. A contact separation detector includes a capacitive element configured to be coupled across a pair of electrical contacts and a current sensor coupled to the capacitive element, configured to measure a current through the capacitive element and output an indication of a separation state of the pair of electrical contacts based on the current as measured.

PRIORITY

This application claims priority under 35 U.S.C. 119(e) to U.S. Provisional Application No. 61/707,373, “ARC SUPPRESSOR,” filed Sep. 28, 2012, which is incorporated herein in its entirety.

This application claims priority under 35 U.S.C. 119(e) to U.S. Provisional Application No. 61/788,786, “ARC SUPPRESSOR,” filed Mar. 15, 2013, which is incorporated herein in its entirety.

TECHNICAL FIELD

The present application relates generally to electrical contact separation detection.

BACKGROUND

Electrical current contact arcing may have a deleterious effects on electrical contact surfaces, such as of relays and certain switches. Arcing may degrade and ultimately destroy the contact surface over time and may result in premature component failure, lower quality performance, and relatively frequent preventative maintenance needs. Additionally, arcing in relays, switches, and the like may result in the generation of electromagnetic interference (EMI) emissions. Electrical current contact arcing may occur both in alternating current (AC) power and in direct current (DC) power across the fields of consumer, commercial, industrial, automotive, and military applications. Because of its prevalence, there have literally been hundreds of specific means developed to address the issue of electrical current contact arcing.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings.

FIG. 1 is a diagram of a system including an arc suppressor, in an example embodiment.

FIG. 2 is a block diagram of an example of an arc suppressor, in an example embodiment.

FIGS. 3A-3G are schematic diagrams of example embodiments of contact separation detectors.

FIGS. 4A-4E depict schematic diagrams illustrating example embodiments of indicators.

FIG. 5 is a flowchart for detecting contact separation, in an example embodiment.

FIG. 6 is a flowchart for making a contact separation detector, in an example embodiment.

DETAILED DESCRIPTION

Previous efforts to suppress arcs have attempted to detect arcs that are generated over electrical contacts. However, arcs may develop so quickly and suddenly that such detectors may not provide an output fast enough to suppress or mitigate the arc quickly enough to substantially reduce the damage to the electrical contacts. By the time such arc detectors detect the arc, the arc may already have reached damaging levels.

A contact separation detector has been developed that may detect a condition indicative of a separation of the contacts, such as a change in voltage and/or current, as disclosed herein, and output an indication of the contact separation. The condition indicative of separation of the contacts may be an electrical signal that may be detected by the contact separation detector. The electrical signal may be generated by the separation of the contacts themselves or by various stages of the formation of an arc that may form as a result of the separation of the contact. The indication may be output to a bypass over the contacts which may be engaged to bypass the contacts to suppress a resulting arc. Alternatively or additionally, the indication may be provided to an indicator, such as an audio, visual, or electronic data indicator, which may indicate one or both of contact separation and arc suppression.

In various examples, the contact separation detector may monitor and indicate the status of a contact. While the contact separation detector disclosed herein will be discussed in particular with respect to electrical contacts, it is to be recognized and understood that the contact separation detector may be applicable with respect to other electrical members between which an arc may form, such as fixed electrodes and the like. In various examples, the contact separation detector may detect electrical changes related, at least in part, to the contact, such as contact voltage and current through an RC circuit coupled over the contact. In various examples, the contact separation detector does not have a significant power-on current pass through. In various examples, the contact separation detector does not singly rely on current change detection or voltage change detection for bypass element triggering. Rather, the contact separation detector may utilize or rely upon both current change detection and voltage change detection.

FIG. 1 is a diagram of a system 100 including an arc suppressor 102 as disclosed herein. While the arc suppressor 102 will be discussed herein with respect to electrical contacts, it is to be recognized and understood that the arc suppressor 102 may be equally applicable to any of a variety of components and circumstances in which an arc may tend to form, such as physically fixed electrodes and the like. The discussion of the arc suppressor 102 with respect to electrical contacts does not limit the applicable scope of the arc suppressor 102 only to electrical contacts.

The system 100 includes a power source 104, a contact 106, and a load 108. The power source 104 may be an AC power source or a DC power source. Sources for AC power may include generators, alternators, transformers, and the like. The source for AC power may be sinusoidal, non-sinusoidal, or phase controlled. An AC power source may be utilized on a power grid (e.g., utility power, power stations, transmission lines, etc.) as well as off the grid, such as for rail power. Sources for DC power may include various types of power storage, such as batteries, solar cells, fuel cells, capacitor banks and thermopiles, dynamos, and power supplies. DC power types may include direct, pulsating, variable, and alternating (which may include superimposed AC, full wave rectification and half wave rectification). DC power may be associated with self-propelled applications, i.e., articles that drive, fly, swim, crawl, dive, tunnel, dig, cut, etc.

The contact 106 may be a switch, relay, contactor, or other contact. The contact 106 includes a pair of contacts, such as electrodes, as illustrated herein. As noted above, the contact 106 may alternative be a static electrode or electrodes or other component over which an arc may tend to form. The load 108 may be a general purpose loads, such as consumer lighting, computers, data transfer switches, etc. The load 108 may be a resistive load, such as a resistor, heater, electroplating device, etc. The load 108 may be a capacitive load, such as a capacitor, capacitor bank, power supply, etc. The load 108 may be an inductive load, such as an inductor, transformer, solenoid, etc. The load 108 may be a motor load, such as a motor, compressor, fan, etc. The load 108 may be a tungsten load, such as a tungsten lamp, infrared heater, industrial light, etc. The load 108 may be a ballast load, such as a fluorescent light, neon light, light emitting diode (LED), etc. The load 108 may be a pilot duty load, such as a traffic light, signal beacon, control circuit, etc.

In the illustrated example, connection between the power source 104 and the contact 106 is via a non-switched contact current node 110. Connection between the contact 106 and the arc suppressor 102 is optionally via a wire connection 112 affixed to a wire terminal 114 of the arc suppressor 102. Connection between the contact 106 and the load 108 is optionally via a switched contact current node 116. A second connection between the contact 106 and the arc suppressor 102 is optionally via a wire connection 118 affixed to a wire terminal 120 of the arc suppressor 102. Connection between the load 108 and the power source 104 is optionally via a return wire connection 122. Thus, the arc suppressor 102 is connected directly in parallel with the contact 106 to be protected.

The arc suppressor 102 may optionally be coupled to an external power supply via a power supply connection 124. The arc suppressor 102 may further optionally be coupled to an external status monitor via a status monitor connection 126. It is emphasized that, as with various components of the system 100, while the power supply connection 124 and status monitor connection 126 are illustrated, such components are optional and may not be included in various examples of the system 100.

Arc Suppressor Block Diagram

FIG. 2 is a block diagram of an example of the arc suppressor 102. The arc suppressor 102 optionally includes some or all of a contact separation detector 200, an indicator 202, a processor 204, a contact bypass circuit 206, a component protection circuit 208, a protection circuit 210, a connection termination 212, a power connection 214, and a power supply 216. While the contact separation detector 200 disclosed herein may be described with respect to contacts, it is to be understood that the contact separation detector 200 may be applicable to detecting an arc generally without respect to contact separation. Thus, in examples in which the arc suppressor 102 is utilized with respect to components other than contacts, the contact separation detector 200 may be understood as an arc detector or arc condition detector.

The block diagram of the arc suppressor 102 includes elements of the arc suppressor 102 generically and without respect to specific voltage, current or power ratings. In various specific implementations, the various blocks may be scaled according to component ratings such as, but not limited to, resistance, capacitance, inductance, voltage, current, power, tolerance, and transformation ratio, to construct specific arc suppressors.

The contact separation detector 200 may detect a condition indicative of a separation of the contact 106, such as a change in voltage and/or current, as disclosed herein. The condition indicative of the separation of the contacts 106 may more generally be a condition indicative of an arc or a formation of an arc, and circumstances in which the contact separation detector 200 is utilized without respect to contacts may produce a detection and an indication of an arc or a condition indicative of an arc. The contact separation detector 200 may, in various examples, output an analog signal that, at relatively low values, indicates a condition, such as a contact separation state, that may not necessarily result in the bypass of the contacts 106. The contact separation detector 200 may, in various examples, output an analog signal that, at relatively higher values, indicates the formation of an arc, as disclosed herein, that may result in bypassing the contacts 106. The values of those indications may be dependent on the circumstances in which the contact separation detector 200 is applied and may be utilized by one or more of the indicator 202, processor 204, and bypass 206 to variously indicate the separations state of the contact 106, indicate an arc condition over the contact 106, and/or bypass the contact 106, as appropriate.

The contact separation detector 200 may output an indication of the contact separation. As illustrated, the indicator is provided to the processor 204. However, in various examples, the indicator may be provided, alternatively or additionally, to the indicator 202 and/or to the contact bypass circuit 206 without respect to the processor 204. On the basis of receiving the indication, the processor 204 may output a trigger signal to engage the electrical bypass of the contact bypass circuit 206 over the contact 106. Alternatively, the contact bypass circuit 206 may receive the indication directly from the contact separation detector 200 and engage the bypass over the contact 106. By bypassing the contact 106 during at least a portion of the time during which the arc may form or tend to form over the contact 106, the energy over the contact 106 may be reduced to levels that may not produce an arc until the conditions within the contact 106 that may cause an arc have passed or otherwise subsided.

The component protection circuit 208 and the protection circuit 210 may provide protection for the various components within the arc suppressor 102. In various examples, the component protection circuit 208 includes one or more of a varistor, a transient voltage suppressor, and back-to-back Zener diodes coupled in parallel with one or more of the contact separation detector 200, the processor 204, and the contact bypass circuit 206. In various examples, the protection circuit 210 includes one or more of a fuse, a resistor, a circuit breaker, and a fusible link coupled in series with one or more of the contact separation detector 200, the processor 204, the contact bypass circuit 206, and the component protection circuit 208.

The connection termination 212 may be a component of the contact 106 itself and may, in various examples, not be considered a component of the arc suppressor 102. In various alternative examples, the arc suppressor 102 may be considered an integral component of the contact 106. The contact termination 212 may be one or more of wire terminals, a pluggable connector, a card-edge connector, and flying leads. The power connection 214 and power supply 216 may optionally supply power to the arc suppressor 102 as a whole, such as to the processor 204. The power connection 214 may be any one or more of wire terminals, a pluggable connector, a card-edge connector, flying leads, and a power connector. The power supply 216 may be any one or more of a battery, a capacitor, one or more voltage regulators, and one or more power regulators.

The arc suppressor 102 may be implemented according to any of a variety of embodiments of some or all of the blocks 200, 202, 204, 206, 208, 210, 212, 214, 216. While specific embodiments are presented in detail herein, it is to be understood that alternative embodiments may be implemented. The particular embodiments may be configured to provide desired performance characteristics, such as for the circumstances in which the arc suppressor 102 is used. The particular embodiments disclosed herein are for the purposes of example and illustration and are not limiting on the implementations disclosed herein.

Contact Separation Detector

FIGS. 3A-3G are schematic diagrams of examples of contact separation detectors. The various contact separation detectors may be utilized in the arc suppressor 102 as the contact separation detector 200. However, it is to be recognized and understood that the contact separation detectors disclosed herein may be applicable in any of a variety of circumstances in the detection of the separation of electrical contacts.

In general, the contact separation detectors disclosed herein may detect one or both of a change in voltage over the contact 106 as the contact separates and a change in current through the contact separation detector owing to the separation of the contact 106. The generation of at least one of a current change or a voltage change in one or more components of the contact separation detector may cause an output that may be indicative of the separation of the contact 106. The output may be utilized to suppress an arc within the contact 106 or for any other suitable purpose.

It is to be noted and recognized that the contact separation detectors may be utilized to detect an arc or an indication of an arc generally without necessarily detecting the separation of contacts. In various examples, the contact separation detector may have separate thresholds that may provide different indications for contact separation and arc detection. A relatively low-voltage indication may indicate contact separation while a relatively higher voltage indicator signal may indicate an arc or the initiation of an arc, as disclosed herein. Thus, the contact separation detectors disclosed herein may be understood to be arc detectors and may be utilized without respect to contacts and/or may be utilized to detect conditions related to arcing in general. However, it is to be recognized that the condition detected by the contact separation detector may be directly indicative of the separation of contacts.

In various examples, the contact separation detector measures the current of an RC circuit using a current sense transformer. In various examples, the contact separation detector measures the current of the RC circuit using a current sensor. In various examples, the contact separation detector measures the current of the RC circuit using a Hall Effect sensor. In various examples, the contact separation detector measures the current of the RC circuit using a transformer. In various examples, the contact separation detector measures the current of the RC circuit using an inductor. In various examples, the contact separation detector may monitor a contact status without ultimately resulting in arc suppression. While the contact separation detectors disclosed herein reference particular components, such as resistors and capacitors, it is to be recognized and understood that the components are illustrated with respect to their electrical properties and that any suitable component, such as a resistive element or a capacitive element in general, respectively, may be readily substituted.

FIG. 3A depicts a schematic diagram illustrating an example of a contact separation detector 300. The contact separation detector 300 as illustrated includes an inductor 302 in series with a first capacitor 304, a second capacitor 306, and a resistor 308. The capacitors 304, 306 and the resistor 308 may function, individually or as a whole, as an RC circuit, as known in the art.

As illustrated, a bridge rectifier 310 is coupled over the inductor 302. The bridge rectifier 310 may measure the current through the RC circuit by producing an output based on a voltage change over the inductor 302. The change in voltage over the inductor 302 is subject to full-wave rectification to provide a higher-voltage DC pulse. An RC filter 312 provides filtering of the rectified output of the bridge rectifier 310. The output of the RC filter 312 may thus act as an indication of a separation state of the contact 106.

FIG. 3B depicts a schematic diagram illustrating an example of a contact separation detector 314. The contact separation detector 314 as illustrated includes a transformer 316 in series with a capacitor 318 and a resistor 320 that may function as an RC circuit, as known in the art. In an example, the capacitor 318 is a 0.1 microFarad capacitor, the resistor 320 is a ten (10) Ohm resistor, and the transformer is a 1:100 transformer. As illustrated, a bridge rectifier 322 is coupled over the inductor transformer 316. The bridge rectifier 322 may indicate a current through the RC circuit by producing an output based on a voltage change over the inductor transformer 316. The change in voltage over the transformer 316 is subject to full-wave rectification to provide a higher-voltage DC pulse than what may be present in the change over the transformer 316. An RC filter 324 provides filtering of the rectified output of the bridge rectifier 322. The output of the RC filter 324 may thus act as an indication of a separation state of the contact 106.

FIG. 3C depicts a schematic diagram illustrating an example of a contact separation detector 326. The contact separation detector 326 as illustrated includes a Hall-effect switch 328 in series with a capacitor 330 and a resistor 332 that may function as an RC circuit. The Hall-effect switch 328 may produce an output indicative of a current through the RC circuit based on a sensed magnetic field induced by the current through the RC circuit. The current output of the Hall-effect switch 328 may act as an indication of a separation state of the contact 106. The output of the Hall-effect switch 328 may be a binary state indication of contact separation and the Hall-effect switch 328 may be selected according to a desired threshold to indicate a binary condition of a contact separation state based on the input to the Hall-effect switch 328.

FIG. 3D depicts a schematic diagram illustrating an example of a contact separation detector 334. The contact separation detector 334 as illustrated includes a Hall effect current sensor 336 coupled in series between a capacitor 338 and a resistor 340 that may function as an RC circuit. In an example, the capacitor 338 has a capacitance of 0.1 microFarads and the resistor has a resistance of one hundred (100) Ohms. The Hall-effect current sensor 336 may produce an output indicative of a current through the RC circuit based on a sensed magnetic field induced by the current through the RC circuit. The current output of the Hall-effect current sensor 336 may act as an indication of a separation state of the contact 106. In contrast to the Hall-effect switch 328, the Hall-effect current sensor 336 may produce an analog output that is indicative not of a binary state but of a variety of potential states, such as that contacts have separated or that an arc has formed or is in the process of forming, as disclosed herein.

The examples illustrated in FIGS. 3E-3G incorporate isolation elements, such as solid state relay, an opto-triac, and an opto-transistor. It is to be recognized and understood that alternative examples that include alternative isolation elements may be utilized in addition to or in place of the isolation elements disclosed herein.

FIG. 3E depicts a schematic diagram illustrating an example of a contact separation detector 342. The contact separation detector 342 as illustrated includes a bridge rectifier 344 in series with a capacitor 346 and a resistor 348 that may function as an RC circuit. A solid state relay 350 is coupled over the output of the bridge rectifier 344. The solid state relay 350 may produce an output indicative of a current through the RC circuit based on the output of the bridge rectifier 344. The output of the solid state relay 350 may act as an indication of a separation state of the contact 106.

FIG. 3F depicts a schematic diagram illustrating an example of a contact separation detector 352. The contact separation detector 352 as illustrated includes a bridge rectifier 354 in series with a capacitor 356 and a resistor 358 that may function as an RC circuit. An opto-triac 360 is coupled over the output of the bridge rectifier 354. The opto-triac 360 may produce an output indicative of a current through the RC circuit based on the output of the bridge rectifier 354. The output of the opto-triac 360 may act as an indication of a separation state of the contact 106.

FIG. 3G depicts a schematic diagram illustrating an example of a contact separation detector 362. The contact separation detector 362 as illustrated includes a bridge rectifier 364 in series with a capacitor 366 and a resistor 368 that may function as an RC circuit. An opto-transistor 370 is coupled over the output of the bridge rectifier 364. The opto-transistor 370 may produce an output indicative of a current through the RC circuit based on the output of the bridge rectifier 364. The output of the opto-transistor 370 may act as an indication of a separation state of the contact 106.

Indicator

FIGS. 4A-E depict schematic diagrams illustrating examples of indicators. The indicators may be incorporated in the arc suppressor 106 as the indicator 202 for the purposes of providing a visual, audio, or electrical output indication of a separation of the contact 106. It is to be understood that the indicators are optional and may not intentionally influence the operation of the arc suppressor 102 as a whole.

FIG. 4A depicts a schematic diagram illustrating an example of an indicator 400 including an LED 402 in series with a resistor 404. The input to the resistor may be coupled to an output of the contact separation detector 200 and/or to the output of the processor 204. A current from the contact separation detector 200 and/or the processor 204 may cause the LED 402 to emit light upon the condition indicative of a separation of the contact 106 is detected, as disclosed herein.

FIG. 4B depicts a schematic diagram illustrating an example of an indicator 406 including first and second LEDs 408, 410, each in series with a first and second resistor 412, 414, respectively. It is to be recognized and understood that the number of LEDs may be increased to provide indications as desired. The indicator 406 may provide multiple indications, such as an output from each of the contact separation detector 200 and the processor 204, such as that may, for instance, inform an observer of a condition that meets a threshold for contact separation but not arc suppression.

FIG. 4C depicts a schematic diagram illustrating an example of an indicator 416 including a speaker 418 configured to provide an audible output. As illustrated, the speaker 418 is in series with a resistor 420 sized to provide a suitable voltage drop over the speaker 418. A current from the contact separation detector 200 and/or the processor 204 may cause the speaker 418 to create an audible tone upon the condition indicative of a separation of the contact 106 is detected, as disclosed herein.

FIG. 4D depicts a schematic diagram illustrating an example of an indicator 422 including a piezoelectric transducer 424 configured to provide an audible output. As illustrated, the piezoelectric transducer 424 is in series with a resistor 426 sized to provide a suitable voltage drop over the speaker 424. A current from the contact separation detector 200 and/or the processor 204 may cause the piezoelectric transducer 424 to create an audible tone upon the condition indicative of a separation of the contact 106 is detected, as disclosed herein.

FIG. 4E depicts a schematic diagram illustrating an example of an indicator 428 including a transmission line driver 430 configured to transmit an indication of a separation of the contact 106 to a secondary device (not pictured). The secondary device may be any of a variety of devices that may utilize information relating to a separation status of the contact 106. The transmission line driver 430 may reproduce a voltage or current as received from the contact separation detector 200 and/or the processor 204.

In various examples, the indicator 204 may be configured to indicate one or more of: assumed arcing; connection failure of the contact; failure external to the contact 106, such as with respect to the power supply 104; failure codes; failure internal to the contact 106, such as a failure of the contact 106 to separate when commanded; a number of events, such as a number of contact separations over time; a rate of events; internal health of the arc suppressor 102; contact separation; triggerable events; an internal indicator, such as data to the processor 204; an output to an external device processing the indicator signal; an output to an external indicator; contact separation detection; and the calculation of an arc suppression factor.

Flowcharts

FIG. 5 is a flowchart for detecting contact separation. The flowchart may be applicable to the contact separation detector 200 or to any other suitable circuit or system.

At 500, a current through a capacitive element coupled across a pair of electrical contacts is measured with a current sensor. In an example, a resistor is in series with the capacitive element, the resistor and capacitive element forming an RC circuit, the RC circuit being in parallel with the pair of electrical contacts, the current sensor being coupled to the RC circuit. In such an example, measuring the current comprises measuring the current through the RC circuit.

At 502, an indication of a separation state of the pair of electrical contacts is output, with the current sensor based on the current as measured. In an example, the current sensor includes an inductor in series with the capacitive element and the resistor. In such an example, outputting the indication of the separation state is based on a voltage as generated by the inductor based on a current through the inductor and the RC circuit. In an example, the current sensor further includes a bridge rectifier coupled to the inductor. In such an example, outputting the indication of the separation state is based on the voltage as generated by the inductor. In an example, the current sensor further includes a transformer, the inductor being a component of the transformer, coupled in parallel with the bridge rectifier and in series with and between the capacitive element and the resistor.

In an example, the current sensor further includes a bridge rectifier coupled in series with the RC circuit and, coupled to the RC circuit, at least one of: a relay, an opto-triac, and an opto-transistor. In such an example, outputting the indication of the separation state is by the at least one of the relay, the opto-triac, and the opto-transistor are configured to output. In an example, the current sensor is a Hall effect sensor. In an example, the Hall effect sensor is at least one of a Hall effect current sensor and a Hall effect switch. In an example, the current sensor includes an input terminal and an output terminal and an isolation component providing at least partial electrical isolation between the input terminal and the output terminal. In an example, the current sensor includes at least one of electromagnetic isolation and optical isolation. In such an example, the current sensor comprises at least one of a Hall effect current sensor, a Hall effect switch, an opto-triac and an opto-transistor.

FIG. 6 is a flowchart for making a contact separation detector. The flowchart may be applicable to the contact separation detector 200 or to any other suitable circuit or system.

At 600, a capacitive element is coupled across a pair of electrical contacts.

At 602, a current sensor is coupled to the capacitive element, the current sensor being configured to measure a current through the capacitive element and output an indication of a separation state of the pair of electrical contacts based on the current as measured. In various examples, the current sensor is a Hall effect sensor. In various examples, the Hall effect sensor is at least one of a Hall effect current sensor and a Hall effect switch. In various examples, the current sensor includes an input terminal and an output terminal and an isolation component configured to provide at least partial electrical isolation between the input terminal and the output terminal. In an example, the current sensor includes at least one of electromagnetic isolation and optical isolation. In an example, the current sensor comprises at least one of a Hall effect current sensor, a Hall effect switch, an opto-triac and an opto-transistor.

At 604, a resistor is coupled in series with the capacitive element, the resistor and capacitive element forming an RC circuit, the RC circuit being in parallel with the pair of electrical contacts, the current sensor being coupled to the RC circuit.

At 606, an inductor of the current sensor is coupled in series with the capacitive element and the resistor, wherein the indication of the separation state is based on a voltage as generated by the inductor based on a current through the inductor and the RC circuit.

At 608, a bridge rectifier of the current sensor is coupled to the inductor and configured to provide the indication of the separation state based on the voltage as generated by the inductor.

At 610, a transformer, of which the inductor is a component, is coupled in parallel, with the bridge rectifier and in series with and between the capacitive element and the resistor.

At 612, a bridge rectifier is coupled in series with the RC circuit and at least one of a relay, an opto-triac, and an opto-transistor is coupled to the RC circuit and configured to ouput the indication of the separation state.

ADDITIONAL EXAMPLES

The description of the various embodiments is merely exemplary in nature and, thus, variations that do not depart from the gist of the examples and detailed description herein are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.

In Example 1, an electrical circuit or system includes a capacitive element configured to be coupled across a pair of electrical contacts and a current sensor coupled to the capacitive element, configured to measure a current through the capacitive element and output an indication of a separation state of the pair of electrical contacts based on the current as measured.

In Example 2, the electrical circuit of Example 1 optionally further includes a resistor in series with the capacitive element, the resistor and capacitive element forming an RC circuit, the RC circuit being in parallel with the pair of electrical contacts, the current sensor being coupled to the RC circuit.

In Example 3, the electrical circuit of any one or more of Examples 1 and 2 optionally further includes that the current sensor comprises an inductor in series with the capacitive element and the resistor, wherein the indication of the separation state is based on a voltage as generated by the inductor based on a current through the inductor and the RC circuit.

In Example 4, the electrical circuit of any one or more of Examples 1-3 optionally further includes that the current sensor further comprises a bridge rectifier coupled to the inductor and configured to provide the indication of the separation state based on the voltage as generated by the inductor.

In Example 5, the electrical circuit of any one or more of Examples 1-4 optionally further includes that the current sensor further comprises a transformer, the inductor being a component of the transformer, coupled in parallel with the bridge rectifier and in series with and between the capacitive element and the resistor.

In Example 6, the electrical circuit of any one or more of Examples 1-5 optionally further includes that the current sensor further comprises a bridge rectifier coupled in series with the RC circuit and, coupled to the RC circuit and configured to output the indication of the separation state, at least one of: a relay, an opto-triac, and an opto-transistor.

In Example 7, the electrical circuit of any one or more of Examples 1-6 optionally further includes that the current sensor is a Hall effect sensor.

In Example 8, the electrical circuit of any one or more of Examples 1-7 optionally further includes that the Hall effect sensor is at least one of a Hall effect current sensor and a Hall effect switch.

In Example 9, the electrical circuit of any one or more of Examples 1-8 optionally further includes that the current sensor includes an input terminal and an output terminal and an isolation component configured to provide at least partial electrical isolation between the input terminal and the output terminal.

In Example 10, the electrical circuit of any one or more of Examples 1-9 optionally further includes that the current sensor includes at least one of electromagnetic isolation and optical isolation.

In Example 11, the electrical circuit of any one or more of Examples 1-10 optionally further includes that the current sensor comprises at least one of a Hall effect current sensor, a Hall effect switch, an opto-triac and an opto-transistor.

In Example 12, a method includes measuring, with a current sensor, a current through a capacitive element coupled across a pair of electrical contacts and outputting, with the current sensor, an indication of a separation state of the pair of electrical contacts based on the current as measured.

In Example 13, the method of Example 12 optionally further includes that a resistor is in series with the capacitive element, the resistor and capacitive element forming an RC circuit, the RC circuit being in parallel with the pair of electrical contacts, the current sensor being coupled to the RC circuit, wherein measuring the current comprises measuring the current through the RC circuit.

In Example 14, the method of any one or more of Examples 12 and 13 optionally further includes that the current sensor includes an inductor in series with the capacitive element and the resistor, wherein outputting the indication of the separation state is based on a voltage as generated by the inductor based on a current through the inductor and the RC circuit.

In Example 15, the method of any one or more of Examples 12-14 optionally further includes that the current sensor further includes a bridge rectifier coupled to the inductor, wherein outputting the indication of the separation state is based on the voltage as generated by the inductor.

In Example 16, the method of any one or more of Examples 12-15 optionally further includes that the current sensor further includes a transformer, the inductor being a component of the transformer, coupled in parallel with the bridge rectifier and in series with and between the capacitive element and the resistor.

In Example 17, the method of any one or more of Examples 12-16 optionally further includes that the current sensor further includes a bridge rectifier coupled in series with the RC circuit and, coupled to the RC circuit, at least one of: a relay, an opto-triac, and an opto-transistor, wherein outputting the indication of the separation state is by the at least one of the relay, the opto-triac, and the opto-transistor are configured to output.

In Example 18, the method of any one or more of Examples 12-17 optionally further includes that the current sensor is a Hall effect sensor.

In Example 19, the method of any one or more of Examples 12-18 optionally further includes that the Hall effect sensor is at least one of a Hall effect current sensor and a Hall effect switch.

In Example 20, the method of any one or more of Examples 12-19 optionally further includes that the current sensor includes an input terminal and an output terminal and an isolation component providing at least partial electrical isolation between the input terminal and the output terminal.

In Example 21, the method of any one or more of Examples 12-20 optionally further includes that the current sensor includes at least one of electromagnetic isolation and optical isolation.

In Example 22, the method of any one or more of Examples 12-20 optionally further includes that the current sensor comprises at least one of a Hall effect current sensor, a Hall effect switch, an opto-triac and an opto-transistor.

In Example 23, a method includes coupling a capacitive element across a pair of electrical contacts and coupling a current sensor to the capacitive element, the current sensor being configured to measure a current through the capacitive element and output an indication of a separation state of the pair of electrical contacts based on the current as measured.

In Example 24, the method of Example 23 optionally further includes coupling a resistor in series with the capacitive element, the resistor and capacitive element forming an RC circuit, the RC circuit being in parallel with the pair of electrical contacts, the current sensor being coupled to the RC circuit.

In Example 25, the method of any one or more of Examples 23 and 24 optionally further includes that the current sensor includes an inductor, further comprising coupling the inductor in series with the capacitive element and the resistor, wherein the indication of the separation state is based on a voltage as generated by the inductor based on a current through the inductor and the RC circuit.

In Example 26, the method of any one or more of Examples 23-25 optionally further includes that the current sensor further includes a bridge rectifier, further comprising coupling the bridge rectifier to the inductor and configured to provide the indication of the separation state based on the voltage as generated by the inductor.

In Example 27, the method of any one or more of Examples 23-26 optionally further includes that the current sensor further includes a transformer, the inductor being a component of the transformer, further comprising coupling the transformer in parallel with the bridge rectifier and in series with and between the capacitive element and the resistor.

In Example 28, the method of any one or more of Examples 23-27 optionally further includes that the current sensor further includes a bridge rectifier, further comprising coupling the bridge rectifier in series with the RC circuit and, coupled to the RC circuit and configured to output the indication of the separation state, at least one of: a relay, an opto-triac, and an opto-transistor.

In Example 29, the method of any one or more of Examples 23-28 optionally further includes that the current sensor is a Hall effect sensor.

In Example 30, the method of any one or more of Examples 23-29 optionally further includes that the Hall effect sensor is at least one of a Hall effect current sensor and a Hall effect switch.

In Example 31, the method of any one or more of Examples 23-30 optionally further includes that the current sensor includes an input terminal and an output terminal and an isolation component configured to provide at least partial electrical isolation between the input terminal and the output terminal.

In Example 32, the method of any one or more of Examples 23-31 optionally further includes that the current sensor includes at least one of electromagnetic isolation and optical isolation.

In Example 33, the method of any one or more of Examples 23-32 optionally further includes that the current sensor comprises at least one of a Hall effect current sensor, a Hall effect switch, an opto-triac and an opto-transistor.

The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments. These embodiments are also referred to herein as “examples.” Such examples may include elements in addition to those shown and described. However, the present inventor also contemplates examples in which only those elements shown and described are provided.

All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

The above description is intended to be, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment. 

What is claimed is:
 1. An electrical circuit, comprising: a capacitor configured to be coupled across a contact; a current sensor coupled to the capacitor and configured to detect a separation of the contact in progress. 